Question about Maxon MCB-30 40-Channels Base CB Radio

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No sound- audio IC amp ok, squelch circuit or squematic needed- thank you

No sound, broken squelch pot, circuit needed.

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Re: no sound- audio IC amp ok, squelch circuit or...

Well my friend I have same problem with some radio. Maybe you should try just to connect detector to audio amplifier and than make an squelch circuit in AF?

Posted on Aug 13, 2007

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2 Answers

No squelch noise from speaker

would you check that the speaker wire is intact..

May 25, 2008 | Raytheon VHF 53 CB Radio

1 Answer

Meter shows good send & receive strength but no sound from internal or Aux. speaker.

If mic is ruled out (broken connections etc) likely a cap in the audio circuit has opened--this happens a lot when a radio is stored for a long period of time.

Going to need a schematic and a meter to test the caps in the audio circuit--could also be a bad audio chip or connections at it.


Apr 21, 2012 | CB Radios

1 Answer

Power is on and all connected up OK but not getting any volume

Turn the squelch control anti-clockwise all the way, make sure mike is plugged in because it is part of the circuit, if radio is connected to a cb antenna you should get audio sound even if it's static it sound, go to channel 19 the trucker channel tend to pick up more activity.

Apr 04, 2012 | CB Radios

1 Answer

The squelch must be wide open or the whole unit powers down. Is this something I can fix by soldering? It sounds like a bad pot....

No it is NOT a bad Pot, what is happening is that with the Squelch "Open" The "Trigger" for that circuit, is getting "Swamped" by signal, and is shorting out, the MCU, senses this and tells the Power Supply it is drawing too much current, and shuts it down. You will need to troubleshoot this area. It may be a very difficult to find. First you need a service manual.
Above is a USER manual.

Apr 22, 2010 | Midland 75-785 Handheld CB Radio

1 Answer

Squelch circuit

ok here is the awnser you are looking for you acn download the service manual here. go to the radio info section go to the g section look for galaxy dx radios scroll to your radio look for service manual, schematics and download what you are looking for.

Mar 03, 2009 | Galaxy Radios DX-2547 40-Channels Base CB...

2 Answers

Cobra 29 no sound but it picks up

Hello Gentlemen,

It sounds like a problem with the audio output stage of the CB, to test this:

1) get a schematic of the CB
2) unplug and un-install the CB
3) put it onto a workbench, remove the cover, and use a 12volt DC power supply to power it
4) on the schematic find the point where the IF signal goes into the Quadrature Detector and test its level against the schematics level using an if probe and a voltmeter.
5) find the point where the Quadrature detector turns the IF into audio and then using an audio test amplifier see if audio is present at the output of the Quadrature detector.
6) If audio is present then trace the signal through the audio stages, until you find the stage where it drops out
7) if audio is not present, then the problem is the Quadrature detector.
8) In either case troubleshoot and find the bad components and replace them.
9) I would suspect bad capacitors, or a malfunctioning audio output IC.

I hope this helps


Oct 23, 2008 | Cobra 29 LTD CB Radio

1 Answer

Cobra 148gtldx low vol squelch on fm

Hi Mate, the problem you are having in not uncommon in the
COBERA 148 GTL. I suspect that the problem lies in low value uF electro caps drying out (electrolite) causing power down and frequency drift. The capacitors are in two forms..tiny blue tantalum, and standard radial base caps that are grey aluminium
cans with a black stripe,it would be a job for a skilled person in electronics to replace all of them. The square metal cans with a screw ferrite slug are what you use to tune the radio, and as there are lot of them ,and you don't have a circuit diagram ,it would be pot luck finding the right one/s. What you realy need to know is all electronic devices age and hence, no longer do their job.
it would cost more than the set is worth to rebuild it,but if you have the skills ,it can be done. am cb with usb / lsb are a thing of the past now and you would be better off buying a used set that is still in top working order. The uhf sets are useless as was the am sets depending on what you want the sets to do, in convoy.... remote country....useless. Having said that the am/usb/lsb sets are the best of the three because on ssb they tx on about 12 watts rms so you have a better chance of making contact, but don't count on it as hf cb is no longer in
common use.

Jun 22, 2008 | Cobra 148 GTL 120-Channels Base CB Radio

1 Answer

I can't hear through my internal or external cb speaker

Can you hear static when the squelch is at minimum ?. If you can hear static then tere is nothing wrong with the audio system. If you are sure about the squelch, connect goosd speaker directly to the 2 wires coming from the main board bypassing the speker jack. if there is still no sound then the audio amp chip is defective. The audio amp can only be damaged if the output is shorted for a long period of time.

Mar 02, 2007 | Uniden PC78ELITE 40-Channels Base CB Radio

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